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Asus A7V266-E dead? What to check?

Posted on 2009-04-11
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Last Modified: 2013-12-10
My computer stopt working, I didn't display any video. I took out the motherboard and stripped eveyrthing. Only a processor, no memory, no peripherals / cards. Motherboard is partly working as when I connect it to an ATC PSU, the green LED starts burning and when I shortcut pin 4 and 5 on the connector, the fans start. No difference if I take out the processor, but the board for the rest remains dead. No beeps. When I only insert a AGP-8 video card, nothing is displayed. Funny thing is of course that I can sort of power it. Connected the external speaker to the appropriate connector, this one also remains dead. I did not change ANY of the dipswitches or jumpers. Battery seems ok. I don't see any leaking capacitors. What else can I measure (I got a multimeter). Where can I start searching? I'm quite sure 90% is working.

I have a vague idea what might have caused a problem... It might have been that an extension card (TV card) was not inserted for 100%. That might create some nasty side effects??

No idea where to start searching. Processor might be dead, it always ran quite hot, but at a certain moment I changed the fan. And even without a processor, the baord should beep as no memory is installed...
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Question by:georgedb
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by:Callandor
Callandor earned 40 total points
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A motherboard cannot be tested by users without a processor, and even with one in, it is too complex to thoroughly test without expensive equipment.

>It might have been that an extension card (TV card) was not inserted for 100%. That might create some nasty side effects??

Yes, you probably shorted out the PCI connector.  Since the board doesn't power up with just the cpu, it is pointing to a dead motherboard, which you cannot fix.  Only bad capacitors that are obviously leaking can be fixed with common tools.
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by:georgedb
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Indeed looks like a dead mobo, but isn't there a certain chip on it that I can replace? As the whole logic of waking up the board still works (connecting pins 4 and 5) and also shutting down the board still works by shortcircuiting pins 4 and 5 for about 8 secs...
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PCBONEZ earned 85 total points
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That's not entirely true. Capacitors, MOSFET's, other regualtor IC chips, Ferrite Cores, fuses, and miscellaneous other parts are replaced all the time by hobbiests and Electronics techs that have learned the ins and out of how motherboards work and who only have basic tools. (Multimeter and soldering gear.)
Few PC techs bother to learn those skills because it's time intensive (too much time for the money they'd get for the work and the client would be waiting too long to get machine back in service) and it's impossible to know beforehand if the effort will be a success or a complete failure (waste of time.).

- If you NEED this machine going for business or work I would look for another motherboard because even if it can be fixed it will take some time and chance of success is anyone's guess.
- If you are doing this as a hobby project or learning experience then I recommend visiting the forums at www.badcaps.net. The membership there bridges the gap between Electronics tech and PC tech. There are several members there that do component level repair to mobo's professionally (with decades worth of experience) and a large number of experienced hobbyists as well.

That said:

Asus _7xxx series motherboard have lots of cap problems including some caps that go bad but don't bloat. [Chemicon KZG series and OST brand.] They also used a number of brands that do bloat. Bloating includes caps that push the bung (plug) out the bottom. Those may not swell but will look taller than they should be and sometimes tilt to the side. [Have to get in close to tell if a bung is actually pushed out or cap was just poorly mounted.]

The misaligned card may have damaged the motherboard OR the power supply depending on what shorted.

I think you've done this, just restating.
Strip to minimal system.
[mobo, psu, 1 RAM module, CPU, video, no drives connected to mobo or PSU, no other add-in cards.]
If you don't get to a BIOS screen try a different PSU.
In this configuration when you start it.
- What do the fans do? (the PSU fan too)
- - - Do they stay off, do the one-spin kick, or stay on?
If mobo has a short then PSU will start but then protective features can turn in right back off.
You should check each voltage during start to see if it comes up and the goes away.
By each voltage I mean +3.3v, +5v, +12v, -12v, and (if you have it) -5v.
You don't have to check every wire for every voltage, one for each wire is good enough as they are connected together in PSU.
- Do voltages come up and then go away or do they stay? Which ones?
Note: +5vsb should be there at all times the PSU has AC power to it. It doesn't go on-off like the others.
.
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by:Callandor
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Good information provided by PCBONEZ - capacitor replacement is what I see most people attempt, since they are some of the most common problems.  Here's a pinout of the 20-pin motherboard connector that you can check the voltages on: http://pinouts.ru/Power/atxpower_pinout.shtml.  You can force the power supply on by shorting pins 13 and 14 if you are testing the power supply by itself.
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by:PCBONEZ
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Yes shorting pins will kick PSU on and that's fine to test PSU output but don't leave them connected.
You want to -momentarily- short the pins.
If you leave them connected PSU protective shut downs 'may' be defeated by giving and endless start-up signal to the controller IC in the PSU. [Depends on PSU's internal design.]
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by:MrMintanet
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>>Motherboard is partly working as when I connect it to an ATC PSU, the green LED starts burning and when I shortcut pin 4 and 5 on the connector, the fans start. No difference if I take out the processor, but the board for the rest remains dead.

This is either the PSU or the board.  I would try to replace the PSU being it would be the cheapest way to isolate the problem.  If this does not work, I would bet 100 bucks that the board is done.
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by:georgedb
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But why could the PSU be bad? It powers the board in such a way that I can sort of "start" (connecting pins 4 and 5 like pressing the start button). After a start the fans start spinning (same speed, never ending). The PSU now powers also an internal SCSI tapestreamer IN ANOTHER COMPUTER (by the lack of wires). Works great, so the +5/+12/GND are ok. Or, and that's worth measuring, it should be the 3.3V line... Just measured it according to the pinout.ru URL. I see some differences.

First of all the colors don't match:
what should be gray is white
what should be blue is brown
what should be white is blue

Voltage though do match more or less:
+3.3V measures +3.37V
+5 measures +5.47V
+12 measures 10.98V
-5 measures -4.62V
-12 measures -8.98V
All voltages are very stable.

No idea if this is within boundaries, it powers an internal tapestreamer (that's only +5V or +5 and +12) perfectly... The -12V is quite low with -8.98, but I'm not sure if this is due to the load (non).

PC bonez: momentarily connecting 13 and 14 only helps for the duration of connecting, in order to measure voltages, they needed to be connected... Maybe you mix it up with the pins on the mobo, those indeed only need a very quick contact.

No capacitor problem, I can have a real close look to the mobo as it's not build in but on my desk.

By the way, this is definitely a hobby project, enough working computers, it's just that I can't stand that it's not working.
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by:georgedb
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OK, unless there are other suggestions, I declare the mobo as dead... Switched PSU's withthe computer I'm no working on, although I didn't expect a solution here and no beeps, nothing. Inserted a videocard in the AGP-slot, unfortunately I don't have a PCI-videocard (as that could also be the problem, but then again, there should always be beeps), inserted some memory. Nothing happens. The other PSU seems ok.

I'll check ad BadCaps.

Would it be fair to donate the points to PCbonez, that was the most informative answer, or shall I (qually?) split the points? Plz advise...

Regards,

George
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by:PCBONEZ
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PSU and motherboard have parts in parallel that work together. (Primarily noise filters and regulators.)
If one of those parts is broken in either one the parts on the other will be overloaded and can fail too.
-
Additionally anything that causes a power spike or excess current in either mobo or PSU will be felt by the components in the other.

A power surge from the wall socket can ruin the blender.
A short in the blender will trip the main breaker.
- Kind of the same thing. - Effects of electricity go both ways.

ATX Voltage Specs Follow:
+3.3v, +/-5% - [ 3.1v-3.5v ] - okay
+5v,  +/-5% - [ 4.75v-5.25v ] - you are out high
+12v, +/-5% - [ 11.4v-12.6v ] - you are -WAY- out low
-5v, +/-10% - [ 4.5v-5.5v ] - you are out high
-12v, +/-10% - [ 10.8v-13.2v ] - you are -WAY- out low
+5vsb, +/-5% - [ 4.75v-5.25v ] - you didn't say

With the 12v out low and 5v out high your PSU has a regulation problem.
- I've only seen numbers that bad in really cheap PSU's.
- With 12v that low CPU may not even be have power because VRM won't turn on.

Bad PSU may have killed motherboard instead of the other way around.
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by:Callandor
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Colors aren't the most important; the voltages are.  The negative voltages are not too important, as they are no longer used in P4 systems and later.  If you put the PSU under a load like a hard drive, you may see how it holds up when current is required.  Unfortunately, when a power supply goes, as PCBONEZ mentioned, there is a chance other parts connected to it can be knocked out as well.  You'll need to test with a good working PSU to determine if it's just the PSU that is bad.
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by:MrMintanet
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So, with what everyone else has said, get a used but working PSU that is compatible with your ATX board.  Test it out.  It's the easiest way to determine if your board has passed on to the next life. :)  Even if you have to buy a PSU to do this, it's only going to cost 30 bucks.  IMO, that's a pretty cheap diagnosis fee, plus you'll have a working PSU regardless :)
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by:georgedb
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OK, see my previous post, after measuring I switched PSU's... The one in the computer I'm now working on was used to power the faulty board. Although voltages were out of tolerances, that di not seem to be the (only) problem. The PSU I'm now working with on this computer must be 100% ok, as this computer works flawlesly...

Therefore the mobo seems dead. Not a capacitor prob. The other PSU might be gone either, but actually I don't think so. I guess when there is a normal mobo load, the voltages will be ok (didn't measure will plugged to the mobo).

I call it a day. Please have a look at my question reg. splitting the points; plz let me know.

George
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by:Callandor
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You can choose as many comments as you want, if you thought they helped.  If they didn't help, don't give points to them.
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by:PCBONEZ
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-5v went away with the ISA slot except for a few odd-ball early P4 MSI boards.
-12v is still used for something I think but off the top of my head I can't remember what it is.
I'll check.
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by:PCBONEZ
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According it Intel's i845GV Chipset Design Guide it goes to those silly CNR slots if you gave one of those.
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